I'm pretty sure Dahyun and Chaeyoung's names are Dahyeon and Chaeyeong. I heard that many companies (and sometimes it's the idols' choice) change their spelling from "eo" to a "u" to make it easier to pronounce.
I'm pretty sure that "eo" in Korean is pronounced like "uh" and a "u" in Korean is pronounced like "oo".
I read somewhere about this...
I remember Jeongyeon was often called and spelt officially like "Jungyeon" but it changed back to Jeongyeon. I don't think Nayeon's name was ever spelt like Nayun though.
Can anyone confirm this or think so too?